The proliferation of social media platforms has ignited a vigorous debate regarding its impact on public discourse. Proponents often laud these digital arenas for democratizing speech, arguing that they empower marginalized voices and allow for rapid dissemination of vital information outside traditional gatekeeping structures. Indeed, movements for justice have found unprecedented global organizing power online. However, this perceived freedom comes with significant drawbacks. The algorithmic curation inherent to these platforms frequently fosters echo chambers, subjecting users to confirmation bias and ideological silos. Furthermore, the incentives driving engagement often reward sensationalism over substance, leading to the viral spread of misinformation and incivility. Therefore, while social media undeniably enhances connectivity and provides powerful tools for mobilization, its structural tendencies simultaneously threaten the quality of reasoned debate, demanding a critical reassessment of digital literacy alongside platform regulation. Based on the passage, what is the central argument regarding social media's role in public discourse?